W7 PM Metals in the Environment: Regulatory and Risk Concerns
Wednesday, 16 November 2005: 1:50 PM - 5:30 PM in 327-329

(LIN-1117-818292) Development of a copper standard for Michigan's Upper Peninsula waters.

Linton, T¹, DeGraeve, G², Saalfeld, G³, Dimond, W³, Clement, W¹, McIntyre, D¹, Bush, D³, ¹ Great Lakes Environmental Center, Columbus, Ohio, USA² Great Lakes Environmental Center, Traverse City, Michigan, USA³ Michigan Department of Environmental Quality, Lansing, Michigan, USA

ABSTRACT- Recent water quality monitoring and accompanying toxicological data reveal that a number of streams in Michigan′s Upper Peninsula (UP) receiving municipal wastewater discharges are exceeding the current copper water quality standard downstream of the municipal discharges. In a number of those instances, there do not appear to be accompanying adverse impacts on resident aquatic macroinvertebrate or fish communities. These monitoring results suggest that the State's current copper standard may be overprotective for a number of the streams and rivers in the U.P., and perhaps for other Michigan rivers and streams as well. The goal of this research was to develop a regionally-based copper standard(s) applicable to the U.P. using a scientifically defensible approach that accounts for the types of site-specific conditions that exist there. Rivers and streams were selected for evaluation based on water hardness (range: 48–213 mg/L CaCO₃) and DOC (range: 1–28 mg/L). Water was collected from a total of 14 sites (13 rivers and streams) for chemistry analysis and water-effect ratio (WER) determination and estimation (using Cu BLM and corresponding site water chemistry) using 48 h static exposure to Ceriodaphnia dubia. A subset of original sites (n=6) spanning the full range of water hardness and DOC concentration in the UP were sampled seasonally for examining temporal influence on WERs. The data indicate that: i) a single standard for copper in the UP is not appropriate, ii) copper toxicity is highly-dependent on DOC concentration, iii) copper toxicity is poorly correlated with water hardness, and iv) use of a Cu BLM for WER estimation is good to reasonable under most, but not all, circumstances. Modification of Michigan′s copper standard at any given site appears best achieved by extrapolating the WER from measured DOC concentration via the established WER versus DOC regression.

Key words: Copper, Standard, Site-specific, BLM